Along with tea, coffee is the most popular beverage worldwide. While some praise its benefits for health, others are sceptical. According to the capacity to metabolise caffeine, a recent research examined the relationship between coffee intake and renal function issues.
Once the coffee is taken, a specific liver enzyme known as cytochrome CYP1A2 metabolises the absorbed caffeine before it is excreted from the body (this enzyme metabolises other substances from the diet, but also certain drugs).
Once digested, caffeine is excreted in the urine. Depending on the CYP1A2 genetic variations, researchers have recently been interested in a potential connection between coffee intake and renal impairment.
The HARVEST study (Hypertension and Ambulatory Recording Venetia Study), a prospective cohort study carried out on Italian participants with stage 1 arterial hypertension between April 1990 and June 2006, provided the data the researchers utilised to assess this connection.
The researchers monitored 1,180 people in this cohort (aged 18 to 45) who were not receiving treatment for high blood pressure for an average of 7.5 years. They considered many factors, including:
Blood pressure readings taken once a semester after three months of monthly readings;
- the drinking of coffee;
- the CYP1A2 genetic variation.
In those with sluggish metabolisms, drinking too much coffee might cause renal issues.
Three indicators of kidney function showed that when individuals had a genetic variation of CYP1A2 causing a slow metabolization (degradation) of caffeine, the chance of developing kidney issues was raised with a high intake compared to a low consumption:
- The likelihood of albuminuria (> 30 mg of albumin per 24 hours), a sign of renal failure (loss of protein in the urine), is increased by 2.7;
a risk increased by 2.8 for hypertension; a risk multiplied by 2.5 for hyperfiltration (another kidney disease, characterised by a rise in the glomerular filtration rate). - More than three cups of coffee per day were considered heavy intake in this context, as opposed to less than that. On the other hand, people with a genetic variation of CYP1A2 linked to a quick metabolization of caffeine did not show a correlation between coffee intake and renal function.
Limit Your Coffee Intake To Protect Your Kidneys.
In those who metabolise caffeine slowly, exceeding the recommended daily intake of three cups of coffee may be harmful to renal function. This danger does not apply to individuals who metabolise caffeine quickly. However, it is still important to understand who has a slow metabolism and who has a rapid metabolism. About half of the population, according to the study, is a sluggish metabolizer of caffeine. Therefore, a sizeable portion of the population would be at danger of kidney injury by drinking a lot of coffee.
The little research that had been done up to that point on the relationship between coffee and kidney health had tended to favour coffee. Therefore, this new research provides fresh insight and issues a warning on the damaging effects of coffee—as well as of other beverages containing caffeine—on the kidneys. Regardless of your CYP1A2 genetic variation, consuming less than three cups per day or choosing decaffeinated coffee seem to be the two safest choices to protect your kidneys.